Mouse myeloma tumors will be used to study the production and secretion of immunoglobulins (Ig) and provide a model system for approaching problems in human multiple myeloma. These tumors, adapted to tissue culture, will be cloned and variants isolated following mutagenesis with chemical mutagens and chemotherapeutic agents. Lectin-resistant and other types of variants will be sought and a variety of somatic cell genetic, biochemical, and serological methods will be used to analyze the mutant phenotype and the products of the mutant gene. Specifically, the production of Ig will be examined by selecting variants which are either completely blocked in glycosylation or which glycosylate their Ig abnormally. Analysis of these cell lines and the abnormal Ig they produce forms the basis for approaching two problems. 1) The biological function of Ig carbohydrate; i.e., Ig with abnormal or absent carbohydrate can be compared with the parental Ig in vitro and in vivo. At the cellular level, the role of the oligosaccharide in Ig secretion and attachment to the cell surface membrane can be studied. At the molecular level, the influence of the oligosaccharide moiety on the tertiary and quaternary structure and domain-domain interactions will be characterized. In this way, it will be possible to elucidate various structure-function relationships. 2) The regulation of glycosylation; i.e., detailed biochemical analysis of abnormal oligosaccharide moieties will provide insight into the control of glycoprotein synthesis at the post-translational level. The structural characterization of wild type Ig and defective Ig with altered oligosaccharides should have implications for other areas of glycoprotein research involving malignant cells.